Multi-purpose electrode for electron discharge devices



Oct. 8, 1968 w. J. PAYNE ETAL 3,405,306

MULTIPURPOSE ELECTRODE FOR ELECTRON DISCHARGE DEVICES Filed Oct. 11, 1965 WITNESSES g s 1 INVENTORS 6O 43 42 Wesle J. P0 n 1 8 Edward R. ompo n BY W 52- ATTORNEY United States Patent 3,405,306 MULTI-PURPOSE ELECTRODE FOR ELECTRON DISCHARGE DEVICES Wesley J; Payne and Edward R. Campagna, Bath, N.Y.,

assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 11, 1965, Ser. No. 494,343 9 Claims. (Cl. 313-239) This invention relates to electron discharge devices and more specifically to improvement in electrode structures therefor.

In the design of electron tubes having a high frequency range, it has been a typical practice to insert several elements or subassemblies of elements for shielding electrodes from one another to thereby reduce the interelectrode capacities related to the adjacent electrodes. An electron discharge device typically includes a cathode element for the emission of electrons, a control grid element having a plurality of turns of lateral grid wire disposed about the cathode element, a screen grid element having a plurality of turns of lateral grid wire disposed about the control grid element, and an anode element typically including two planar members disposed on either side of the screen grid element and interconnected by straps. Further, the electrodes enumerated above are typically mounted within the envelope of the electron discharge device as by a pair of insulating members disposed on either side of the electrodes and having openings therein to receive tabs or extensions of the electrodes. In order to properly shield such an electron discharge device, the prior art has suggested the insertion of a number of separate elements or subassemblies of elements between the electrodes of the electron discharge device. Typically, these elements would include a beam plate having an enclosed box-like configuration and a window or aperture portion for the passage of electrons and being inserted between the screen grid and the anode elements, and an outer shield of a cylindrical configuration disposed about the anode element so as to surround each of the electrodes of the electron discharge device. In order to properly shield the attaching tabs or extensions of the electrodes, it has been a typical practice of the prior art to insert bottom and top shielding plates which are disposed upon the insulating members and which have portions thereof extending upwardly between the attaching tabs to provide a shielding means between the electrodes and the shielding members which are likewise secured to the insulating members.

It may be well understood that the need for shielding increases as the number of electrodes increase and as a result the cost of manufacturing the electron discharge device will also increase. The forming of each of the shielding members is expensive in terms of materials and labor due to the complexity of their configuration and due to the accuracy with which these members must be made. Further, as the number of the shielding members increase the problems and expense of assembling these parts together are multiplied and the percentage of rejected electron devices increases due to the additional steps necessary to assemble each of these shielding members.

Accordingly, it is the general object of this invention to provide a new and improved electron discharge device.

It is another object of this invention to provide an improved electron discharge device wherein a shielding means may be provided between the electrodes of the electron discharge device without the use of many, separate shielding elements.

It is a still further object of this invention to provide a new and improved shielding means for an electron discharge device which may he easily formed and assembled 3,405,306 Patented Oct. 8, 1968 with the electrodes of the electron discharge device at a minimum cost in materials and labor.

Briefly, the present invention accomplishes the abovecited objects by providing an improved electron discharge device, wherein there is incorporated an integral multipurpose electrode having a portion thereof inserted between a grid element and an anode element of the electron discharge device with an aperture therein for allowing the electrons directed from a cathode element to pass to the anode elements, and an outer portion disposed on an opposite side of the anode element from the inner portion. The inner portion of the multi-purpose member forms an effective beam plate member for focusing the electron beam and also acts to suppress secondary electrons emitted from the anode elements, the outer portion forms an effective peripheral shielding member. The inner shielding portion has extensions disposed upon either end thereof which further provide shielding between the connecting portions of the screen grid and the anode element and which effectively replace separate top and bottom shielding members. In addition, it may be understood that the integral multi-purpose member may include second inner and outer portions which may be disposed symmetrically with respect to the first portions on the opposite side of the cathode element and interconnected to the first mentioned inner portion to form a serpentine shaped members.

Further objects and advantages of the invention will become apparent as the following description proceeds and features of novelty which characterize the invention will be pointed out in particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, reference may be had to the accompanying drawings, in which:

FIGURE 1 shows a partially sectioned view of an electron discharge device in which this invention has been incorporated;

FIG. 2 shows a front view of an electrode assembly which has been incorporated in the electron discharge device of FIG. 1; and

FIG. 3 shows a side view of the shielding member in accordance with the teachings of this invention which has been incoiporated in the assembly of FIG. 2 and in the electron discharge device of FIG. 1.

Referring now to the drawings and in particular to FIG. 1, there is shown an electron discharge device 10 employing the present invention in its preferred form. The electron discharge device 10 is comprised of an envelope 12 made of a suitable material such as glass with an electrode assembly indicated generally by the character 26 enclosed therein. The envelope 12 is of conventional design including a tipped off exhaust 14 on top of the envelope 12 and a button stem header 20 closing off the bottom portion of the envelope 12. A plurality of electrically conductive terminals or lead elements 16 are sealed through the header 20 and are connected to the elements of the electrode assembly 26 by the interconnecting leads 18. The terminals 16 not only supply the necessary voltage to the elements of the electrode assembly 26, but also act in conjunction with a pair of insulating elements 22 and 24 (see FIG. 2) to support the electrode assembly 26 within the envelope 12.

The electrode assembly 26 includes an electron emissive or cathode element 28 of the indirectly heated type which is supported upon and between the insulating elements 22 and 24. A folded heater element 29 is disposed within the cathode element 28 to energize a layer of suitable electron emissive material such as 'a triple carbonate which is disposed upon the peripheral surface of the cathode element 28. A control grid electrode 33 having a pair of side support rods 34 and a plurality of turns of lateral grid wire 35 suspended upon the side support rods 34 is disposed about the cathode element 28 to present active grid portions of the lateral grid wire on either side of the cathode element 28. Further, a screen grid electrode 30 including a pair of side support rods 31 and a plurality of turns of a lateral grid wire 32 suspended upon the side support rods 31. The turns of lateral grid wire 32 are disposed about the control grid electrode 33 to present a pair of active grid portions on either side of the cathode element 28 to traverse the streams of electrons emitted from the cathode element 28. An anode element 36 comprising two plates or segments 39 is disposed on either side of the cathode element 28 to provide surfaces for receiving the eectron beam streams emitted from the cathode element 28. The two plates 39 are structurally and electrically interconnected by a pair of straps 41. The anode element 36 is supported as by the insulating members 22 and 24 so that the plates 39 are disposed in a substantially parallel relationship with the active portions of the grid electrodes 30 and 33. Further, an interconnecting lead 18a is disposed between one of the terminals 16 and the anode element 36 to apply an appropriate voltage thereto.

Referring now to FIGS. 1, 2 and 3, a multi-purpose member 40 will now be described. The member 40 is a unitary member made of a suitable electrically conductive material such as nickel plated steel or aluminum clad steel and includes a plurality of portions which are disposed in a substantially parallel relationship with each other to form an eifective shielding means between the adjacent electrodes of device 10. In the sense of this invention, unitary refers to a member made of a single piece of material. In particular, the shielding member 40 includes a pair of beam plate portions 42 and 44 which are disposed on either side of and in substantially parallel relationship to the electron emissive surfaces of the cathode element 28 and the active portions of the grid electrodes 30 and 33. Rectangular apertures 46 and 47 are provided in the beam plate portions 42 and 44 respectively to focus the electrons emitted from the cathode element 28 upon the segments 39 of the anode element 36. Further, a pair of outer shielding portions 54 and 56 are integrally connected to the portions 42 and 44 respectively by the interconnecting portions 58 and 60. The beam plate portions 42 and 44 are interconnected and supported with respect to each other by a pair of interconnecting straps 48 which are disposed between the portions 42 and 44. It is particularly noted that the multi-purpose member 40 is formed as an integral member in a serpentine configuration.

The multi-purpose member 40 as its name implies serves to perform a plurality of functions and effectively replaces a number of elements normally incorporated in the electron tubes of the prior art. For instance, it is a function of the apertured beam plate portions 42 and 44 to focus the electrons emitted from the cathode element 28 upon the segments 39 of the anode element 36 and to also suppress secondary electrons emitted from the surface of the anode element 36 by the formation of a potential minimum in the area of the apertures 46 and 47.

Further, it is a significant aspect of this invention that the multi-purpose electrode 40 serve as a shielding means between the various electrodes of the device 10. As is well recognized in the art, the presence of certain interelectrode capacitances and in particular the capacitance between the control grid electrode and the anode element is objectionable, and many efforts have been made to reduce the inter-electrode capacitance by the use of shielding members. Such shielding members or means act when inserted between electrodes as a barrier to intercept the electrostatic field established between the electrodes. Thus, as the electrostatic field is decreased between the electrodes, the capacitance therebetween is likewise reduced. Referring now to FIG. 1, is may be seen that the portions 42 and 44 of the multi-purpose member 40 serves as a shielding means between the control grid electrode 33 and the segments 39 of the anode element 36. Though it is necessary to provide the apertures 46 and 47 within the portions 42 and 44 to allow electrons emitted by the cathode element to paSS therethrough, the area of these apertures is minimized to thereby present a maximum shielding area to the lines of the electrostatic field established between the control grid 33 and the anode element 36. The criticality of the inter-electrode capacitance between the control grid and the anode may be understood when it is realized that the efficiency of the device 10 is dependent upon isolating the control grid from the anode element. Further, the interconnecting straps 48 between the portions 42 and 44 are made of a greater width than the straps 41 interconnecting the segments 39 of the anode element 36 to thereby provide effective shielding means between these portions of the anode element and the control grid 33. Though it might be desirable to enclose the area between the straps 48, it is necesary to leave this opening in order to allow gases generated within this confined area and in particular from the emissive coating of the cathode element to be withdrawn during the manufacturing processes. The portions 54 and 56 provide an etfective means for shielding the segments 39 of the anode element 36 from the other elements and in particular the control grid electrode of the electron discharge device 10. It is noted that the lines of the electrostatic field between the control grid 33 and the anode element 36 do not necessarily assume a direct path between these elements, but rather may take arcuate paths around the portions 42 and 44 to strike the segments 39 upon that surface of the segments 39 facing away from the cathode element 28. Thus, the portions 54 and 56 shield these remote surfaces of the segments 39 from the stray lines of electric field that would otherwise be directed towards this surface. As a result, the cylindrical, outer shielding member which is incorporated in electron discharge devices of the prior art may be omitted.

In an illustrative mode of operation, the multi-purpose member 40 and the cathode element 28 are maintained at ground potential while the first grid electrode 33 is maintained at approximately 1 volt negative, and the second or screen grid electrode 30 and the anode element 36 are maintained at approximately 120 volts positive. In this mode, the portions 42 and 44 function to focus the streams of electrons and also to suppress secondary emission from the anode element.

Referring now to FIGS. 1 and 2, there is shown an illustrative manner in which the elements of the electrode assembly 26 may be mounted. Specifically, the elements are disposed between and secured to the pair of insulating members 22 and 24. The anode element 36 has two pairs of tabs 37 extending from either end of the segments 39. The tabs 37 extend upwardly and downward to thereby engage the apertures 67 and 77 within the members 22 and 24. Typically, one of the tabs 37 may be bent over to thereby effect a secure connection between the anode element 36 and the insulating member 24, while another of the tabs 37 extending through aperture 77 may be electrically connected to the lead 18a. Further, the multipurpose member 40 has a plurality of tabs 62 extending from the other shielding portions 54 and 56 to engage the apertures 79 and 69 of the insulating members 24 and 22 respectively. Likewise, the tabs 62 are bent over to secure the multi-purpose member 40 to the insulating members. Two pairs of apertures 64 and 74 are provided respectively in the members 22 and 24 to receive either end of the side support rods 31 and thereby support the screen grid electrode 30. Further, two pairs of apertures 65 and 75 are provided respectively in the members 22 and 24 to receive the end portions of the side support rods 34 to thereby support the control grid electrode 33. Apertures and 81 are provided respectively in the members 22 and 24 to receive in a friction relationship and to support the cathode element 28 which extends therethrough.

As a further aspect of this invention, there are provided a pair of upper extensions 50 and 51 and a pair of lower extensions 52 and 53 which are integrally associated with and extending from the beam plate portions 42 and 44. As shown in FIG. 2, the extensions 50 and 51 are directed upward and pass through the slots 76 within the insulating member 24. The lower extensions 52 and 53 extend downwardly and pass through the slots 66 within the insulating member 22. The extensions 50 and 51 are made of sufficiently greater height than the end portions of the side support rods 31 and 34 so as to effectively shield the anode element 36 from the lines of electrostatic flux emanating therefrom. Further, it is desirable to make the extensions 52 and 53 as long as possible so as to provide effective shielding between the grid electrode and the anode element and also between the interconnecting leads 18 associated with these electrodes and the lead 18a electrically connected to the anode element 36. However, due to considerations of forming the leads 18, it may be necessary to abbreviate the length of 4 the extensions 52 and 53. However, it may be possible to provide an extension portion 52a extending integrally from the extension 52 to shield the lead 18a from the remaining leads of the device and in particular from the lead associated with the control grid electrode 33. As explained above, the lines of the electrostatic field emanating from the grid electrodes do not necessarily travel in a straight line but may take curved paths through the insulating members or may emanate from the end portions of the side support rods to pass about the portions 42 and 44 to strike both surfaces of the segments 39; thus the extensions integrally associated with the portions 42 and 44 provide an additional shielding between the control grid electrode and the anode element and between the interconnecting leads associated therewith. Thus, the top and bottom shielding members of the prior art which a have been disposed upon the insulating members 22 and 24 have been effectively replaced by means integral with the multi-purpose member 40 and which is substantially less expensive to manufacture.

In conclusion, there has been shown and described a multi-purpose member which may be effectively substituted for a plurality of elements within electron discharge devices such as tube types 6JC6 and 6JD6 as manufactured by the assignee of this invention. In particular, the multi-purpose member of this invention replaces the rectangularly shaped beam plate element, the outer cylindrical shield and the shielding plates positioned upon the insulating members. It is noted that these elements are typically incorporated within pentode type devices of the prior art. As a result, the number of steps required to assemble the device of this invention has been reduced. Further, the multi-purpose member described herein may be easily mass produced by stamping from a metal sheet and folding to the desired configuration.

While there has been shown and described what is at present considered to be the preferred embodiments of this invention, modifications thereto will readily occur to those skilled in the art. It is not desired, therefore, that the invention be limited to the specific arrangements shown and described and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

We claim as our invention:

1. An electron discharge device comprising a cathode element for the emission of a stream of electrons, a grid electrode disposed to traverse said stream of electrons, an anode element having first and second surfaces, said first surface being disposed to collect said stream of electrons, and a unitary multi-purpose member having a first portion disposed between said grid electrode and said anode element to suppress secondary electrons emitted from said anode element and a second portion disposed upon the opposite side of said anode element with respect to said cathode element to shield said second surface of said anode element, said first portion having an aperture therein through which said stream of electrons passes and an extension therefrom for shielding said anode element.

2. An electron discharge device comprising a cathode element for the emission of a stream of electrons, a grid electrode disposed to traverse said stream of electrons, an anode element disposed to collect said stream of electrons, a unitary multi-purpose member having a first portion disposed between said grid electrode and said anode element and a second portion disposed upon the opposite side of said anode element with respect to said cathode element, said first portion having an aperture therein through which said stream of electrons passes and an extension for shielding said anode element, and an insulating member for supporting said cathode element, said anode element, said multi-purpose member and said grid electrode, said insulating member having an opening through which said extension extends beyond the surface of said insulating member.

3. An electron discharge device comprising a cathode element for the emission of first and second streams of electrons; a grid electrode having first and second active grid portions which traverse respectively said first and second streams of electrons; an anode element having first and second segments which are disposed respectively to re ceive said first and second streams of electrons; and a multi-purpose member having first, second, third and fourth portions, said first and second portions disposed respectively between said first active grid portion and said first segment, and between said second active grid portion and said second segment, said third and fourth portions disposed upon the opposite sides of said first and second portions respectively with respect to said cathode element, said first and second portions having openings therein through which said streams of electrons pass.

4. An electron discharge device comprising a cathode element for the emission of first and second streams of electrons; a grid electrode including a pair of side support rods and a plurality of turns of lateral grid wire suspended upon said side support rods, said turns of lateral grid wire disposed about said cathode element to provide first and second active portions of said lateral grid wire which traverse respectively s-aid first and second streams of electrons; an anode element having first and second segments disposed respectively to receive said first and second streams of electrons; a unitary, multi-purpose member having first, second, third and fourth portions, said first and second portions of said multi-purpose member disposed respectively between said first active portion and said first segment, and between said second active portion and said second segment, said third and fourth portions of said multi-purpose member disposed respectively upon the opposite sides of said first and second segments with respect to said cathode element, said first and second portions of said multi-purpose member having openings through which said first and second streams of electrons pass respectively and having extensions therefrom; and an insulating member for supporting said cathode element, said grid electrode, said anode element and said multi-purpose member, said insulating member having openings for receiving end portions of said side support rods and said extensions, said extensions extending beyond the surface of insulating members to shield said anode element from said end portions of said side support rods.

5. A unitary, multi-purpose member for an electron discharge device, said electron discharge device including a. cathode element for the emission of first and second streams of electrons, a grid electrode presenting first and second active portions that traverse respectively said first and second streams of electrons, and an anode element having first and second segments, each of said first and second segments having first and second surfaces,

said first surfaces of said first and second segments dis posed to receive respectively said first and second streams of electrons; said multi-purpose member comprising first and second portions for forming said first and second streams of electrons and for suppressing the secondary electrons emitted from said anode element, said first and second portions of said multi-purpose member disposed respectively between said first active portion and said first segment, and between said second active portion and said second segment, each of said first and second portions having openings therein to allow the passage of said streams of electrons, and third and fourth portions, said third and fourth portions of said multi-purpose member being dis-posed upon the opposite sides respectively of said first and second segments with respect to said cathode element to shield said second surfaces of said first and second segments from said grid electrode.

6. An electron discharge device comprising a cathode element for the emission of first and second streams of electrons; a grid electrode having a pair of side support rods and a plurality of turns of lateral grid wire suspended between said side support rods, said turns of lateral grid wire disposed about said cathode element to provide first and second active grid portions that traverse respectively said first and second streams of electrons; an anode element having first and second segments, each of said first and second segments having a first surface disposed towards said cathode element to receive respectively said first and second streams of electrons and a second surface disposed to face away from said cathode element; an integral, multi-purpose member including first, second, third and fourth portions formed in a serpentine configuration, said first and second portions of said multipurpose member disposed respectively between said first active grid portion and said first segment, and between said second active grid portion and said second segment, each of said first and second portions of said multi-purpose member having openings therein through which said streams of electrons pass and having extensions therefrom, said third and fourth portions disposed upon the opposite sides of said first and second segments respectively with respect to said cathode elements, and an insulating member having openings therein for receiving and supporting said side support rods of said grid electrode and said extensions, said extensions extending beyond the surface of said insulating member to shield said second surfaces from said grid electrode.

7. An electrode assembly for an electron discharge device, said electron discharge device including a cathode element for the emission of a stream of electrons, a grid electrode having an active grid portion that traverses said stream of electrons, and an anode element for receiving said stream of electrons; said electrode assembly comprising: a unitary, multi-purpose member having first and second portions, said first portion disposed between said active grid portion and said anode element for shielding said anode element, said first portion having an opening therein through which said stream of electrons pass and having an extension integral with said first portion, said second portion disposed upon the opposite side of said anode element with respect to said cathode element; and an insulating member for supporting said cathode element, said grid electrode, said anode element, and said multi-purpose member, said extension extending beyond the surface of said insulating member to shield said anode element.

8. An electron discharge device comprising an envelope having therein a cathode element for the emission of a stream of electrons, a grid electrode disposed to traverse said stream of electrons, an anode element disposed to collect said stream of electrons, a multi-purpose member having first and second portions, said first portion disposed between said grid electrode and said anode element, said first portion having an aperture therein through which said stream of electrons passes, said second portion disposed upon the opposite side of said anode element with respect to said cathode element, said first portion having an extension integral therewith, and an insulating member for supporting said cathode element, said anode element, said multi-purpose member and said grid electrode; and said first and second electrically conductive means extending through said envelope for applying electrical signals respectively to said anode element and said grid electrode, said extension extending beyond the surface of said insulating member to effectively shield said first electrically conductive means from said second electrically conductive means.

9. An electron discharge device comprising a cathode element for the emission of first and second streams of electrons; a grid electrode providing first and second active grid portions that traverse respectively said first and second stream electrons; an anode element having first and second segments, said first and second segments being interconnected with each other by a first strap member and being disposed to receive respectively said first and second streams of electrons; an integral, multipurpose member including first, seeond, third and fourth portions, said first and second portions of said multi-purpose member disposed respectively between said first active grid portion and said first segment, and between said second active grid portion and said second segment, said first and second portions of said multi-purpose member having openings therein through which said streams of electrons pass, said third and fourth portions disposed respectively upon the opposite sides of said first and second segments with respect to said cathode element, said first and second portions being interconnected by a second strap member, said second strap member having a width sufiiciently greater than that of said first strap member and being disposed between said first strap and said grid electrode to effectively shield said first strap of said anode element from said grid electrode.

References Cited UNITED STATES PATENTS 2,511,143 6/1950 Adler 313-300 X 2,611,879 9/1952 Adler 313-30O X 3,125,699 3/1964 Georgies 3l3299 JOHN W. HUCKERT, Primary Examiner.

R. F. POLISSACK, Assistant Examiner. 

1. AN ELECTRON DISCHARGE DEVICE COMPRISING A CATHODE ELEMENT FOR THE EMISSION OF A STREAM OF ELECTRONS, A GRID ELECTRODE DISPOSED TO TRAVERSE SAID STREAM OF ELECTRONS, AN ANODE ELEMENT HAVING FIRST AND SECOND SURFACES, SAID FIRST SURFACE BEING DISPOSED TO COLLECT SAID STREAM OF ELECTRONS, AND A UNITARY MULTI-PURPOSE MEMBER HAVING A FIRST PORTION DISPOSED BETWEEN SAID GRID ELECTRODE AND SAID ANODE ELEMENT TO SUPPRESS SECONDARY ELECTRONS EMITTED FROM SAID ANODE ELEMENT AND A SECOND PORTION DISPOSED UPON THE OPPOSITE SIDE OF SAID ANODE ELEMENT WITH RESPECT TO SAID CATHODE ELEMENT TO SHIELD SAID SECOND SURFACE OF SAID ANODE ELEMENT, SAID FIRST PORTION HAVING AN APERTURE THEREIN THROUGH WHICH SAID STREAM OF ELECTRONS PASSES AND AN EXTENSION THEREFROM FOR SHIELDING SAID ANODE ELEMENT. 